The upsetting of the thickened ends of tubes (which term includes pipes) is carried out in upsetting presses, and usually requires two, occasionally one or more than two (three or four) operations. Upsetting presses are therefore provided with vertically divided dies having to superposed shaping faces. The dies consist of a front pair of jaws for clamping the tubes and of a rear pair of jaws comprising the shaping faces involved in the upsetting operation. The two operations of preliminary and final upsetting that are usually carried out takes place one after the other in a single heat in the superposed shaping faces of the die. The efficiency of the upsetting operation depends to a considerable extent upon the mode of operation and therefore upon the construction of the loading equipment with which the tubes are manipulated. Thus, in the case of vertically divided dies, it is necessary to bring the tubes exactly into alignment on the middles of the shaping faces before closing the dies and to hold them there until the dies are closed, so as to avoid straining of, and damage to, the tubes.
Very accurate axial positioning of the ends of the tubes in the dies is also necessary, firstly so as to enclose, between the shaping faces, a sufficient amount of material for the upsetting operation, and secondly so as to prevent upsetting defects (dimensional deviations and the formation of folds, particularly in the case of internally thickened tube-ends), for which purpose it is particularly necessary for the transition zone between the hot tube-end and the cold tube to be accurately axially positioned between the shaping faces of the die. In order to limit the flow of heat from the heated tube-end to the cold tube and to keep the transition zone within narrow bounds, considerable importance attaches to a rapid transfer of the tubes from the heating installation to the precise positions for upsetting. The creation of noise during manipulation of the tubes must nevertheless be borne in mind and limited to a low level. Thus, there arises the problem of providing tube-loading equipment that operates accurately, rapidly and with little noise.
Loading equipment previously used for manipulating tubes on upsetting presses of the stated kind consists of a roller bed comprising V-shaped rollers as the means for receiving the tubes to be manipulated, these rollers being mounted on an upwardly and downwardly movable bridge and having reversible drives. The roller bed is loaded from a support grid, which bridges the space between the induction coils for heating the tube ends and the upsetting press and which slopes towards the press. Each tube resting on the roller bed is aligned with the middle of the shaping faces of the die by vertical displacement of the bridge and is moved, by the rollers, axially into and out of the zone of the dies. In operation, these loading systems are too slow, too inaccurate and, in addition, relatively noisy. A further disadvantage resides in the fact that a fresh tube can be manipulated in the upsetting press only when the preceding tube has been removed from the press and the upwardly and downwardly displaceable bridge has been returned to its upper position. Thus, it is not possible to manipulate a second tube in the upsetting press with the result that it is impossible to carry out work simultaneously in two superposed sets of shaping faces of the dies. This loading equipment does not therefore solve the problem whose solution forms the object of the present invention.